Many liquid or gas/liquid spraying devices utilize a nozzle having a spray head which produces a flat fan spray pattern. The most common method to produce such a spray pattern is to dispose an elliptical or rectangular orifice at the tip or discharge end of the spray head, as disclosed in U.S. Pat. No. 5,240,183 ('183 Patent). The drawback of this method is that the spray pattern does not produce a uniform distribution of liquid, especially for two-fluid or gas/liquid spraying devices.
A flat fan spray pattern has also been produced by spray heads having a plurality of circular orifices linearly spaced apart thereon, as disclosed in U.S. Pat. No. 1,485,495 ('495 Patent) and the '183 Patent. The spray head disclosed in the '495 Patent is of rectangular form, while the spray head disclosed in the '183 Patent is cylindrical. To produce the flat fan pattern, each of the orifices is disposed along a given plane and angled outwardly at various angles from the centerline or longitudinal axis of the spray head. It has been found that spray heads such as these tend to produce a nonuniform pattern having areas of high spray density separated by areas of low spray density. Moreover, for a spray head having orifices of a predetermined number and diameter, the greater the angle of the spray emitted from each orifice, as measured from the centerline or spray axis of the spray head, the greater will be the tendency to produce nonuniform spray patterns.
Another drawback of the above-described spray heads for a given orifice diameter, is that the number of spaced linearly aligned orifices disposed on the spray head is limited by the diameter or width of the spray head which, in turn, limits the flow rate of such spray heads which is proportional to the total cross-sectional area of the orifices. In addition, the limited number of orifices would necessitate a greater angle between adjacent orifices for a given spray width thereby producing a nonuniform spray pattern.
A further drawback of the spray head disclosed in the '183 Patent, is that the orifices are disposed at various distances from the longitudinal axis of the mixing chamber. It has been found that in many two-phase systems, such as gas/liquid mixing nozzles, the greatest uniformity of the intermixing of the two phases occurs generally adjacent to the periphery of the mixing chamber whereby the linearly spaced individual orifices do not provide an overall uniform spray pattern.